Electrical load control system



Jan. 15, 1935. R. H. KAUFMANN ELECTRICAL LOAD CONTROL SYSTEM Filed March 15, 1934 5 Sheets-Sheet 1 I I MAX/MUM l DEM/1N0 I I I I I 1 I I FIQI.

6 9 i 4 l l i I I METER C0/V721CT GETTING OEMAND PER/0D TIME I l MAX/MUM DEM/4ND PER/00 HIGH 8E TT/NG LOW GETTING TIME Inventov: Richard H. Kaufm anTI His ttorngy J 1 R. H. KAUFMANN 1,988,278

ELECTRICAL LOAD CONTROL SYSTEM Filed March 15, 1934 3 Sheets-Sheet 2 Inventor: Richard H. Kaufmarm,

by H

is A tornqy- Jan. 15, 1935. R. H. KAUFMANN 1,988,278

ELECTRICAL LOAD CONTROL SYSTEM Filed March 15, 1954 3 Sheets- Sheet 3 Inventor: Richarci H. Kaufmanfi,

His Attorngg- Patented Jan. 15, 1935 1 ELECTRICAL LOAD CONTROL SYSTEM Richard H. Kaufmann, Schenectady,-N. Y., as- 'signor to General Electric Company, a corporation of New York -Application-March 15, 1934, Serial 'No. 715,606

11 Claims. (01. I'll-97) OFFICE Myinvention relates to electrical load control systems and more particularly to automatic electric power. demandlimiting systems.

It is customary for commercial purchasers of electric 'power to pay a charge,.known-as a demand charge,---which .is proportional. to their .maximum demand. Maximum demandmay be defined. as the maximum integratedamount of electrical energy, usually measured in kilowatt 'hours which is used during any one of successive equal time intervals, whose individual durations are known as the demand period. As a result of this way'of' charging-for electrical energy it is to .the advantage of consumers to provide automatic'means for preventing theestablishment .of' higher than necessary maximum demands.

Irraccordance'with my invention Iv provide: a novel automatic maximum demand limiting'system. -Broadly speaking, my system operates during the early part of the demandperiod to reduce the'effective "load value of the consumer substantially in proportion to the average rate of :increase of the. integrated energy be consumes. 'Ihe theory of this is that 'themore rapidly the integrated'energy. required by the load builds up duringthe first part of the demand period, the more the previouslyestablished 'maximum demand is likely to be exceeded and consequently the greater the effective reduction of loadnecessary to prevent this occurrence.

The-way I at. present contemplate securing the above operation is through thesuse of time controlled circuit controllers which operate successively to incapacitatethe circuits for removingloadincrements; so that depending upon the timerequired for a predetermined fraction of the maximumwdemand'to. be "attained, the number of removed load increments, or the amount of load reduced, will vary inversely with this time.

I wish-to point out, however; "that Jmyinvention is entirely. independentv of the particular way infwhich the'efiectiveload on. a power circuit is'reduced. Thus, there are two well known ;..'main ways of controlling or reducingthe'efifective value of load .on a power circuit, one way being to control the load itself and. the other way being to control an auxiliary source of current supply for assuming a part of the load. -Both ways produce the same'riet result on the main power circuitin that the efiective load value is'reduced. Furthermore, there are a great many. equivalent ways of reducing "the value of theload itself. Thus, in 'the caseof loads hating the. principles of operation of my invenlike electrode furnaces, .load may be controlled in infinitely small increments by electrode .con-

.trol,. whereasin I the .case of loads comprising. a

pluralityrof. paralleLconnected load. devices, such as-lelectric.motors, .load may be controlled by disconnecting oneormmore of the motors entirely from .theeircuit, sothatin this case the load is controlled in positiveincrements of appreciable value.

. -An-object of-my inventionis toprovide a new and. improved electrical load control system.

.- .A. turther objectofmy invention .isto provide a new and improvedautomaticmaximum power demand limiting. system.

. .My inventionwill be better understood irom the following description-taken in.- connection with theaaccompanying drawingsand its scope will be pointedoutinthe. appended claims. In the drawings, Fig. l is achart for illustionyFig; 2-is a chart 'for illustrating the prin- .ciples of-.operation of a;- modified form of my. in-

vention; Fig. 3 .is a simplified. diagrammatic showingof an embodiment of. my invention whichoperates according to Fig. 1; Fig. 4 'is a simplified diagrammaticshowing of a-..modiflcaation-of my. invention which operates according to Fig. 2; and Fig. 5i'is a diagrammatic .view of a commercially more practicalsystem than the systemillustrated in Fig.- 3.

Turning .nowto Fig. 1 of the accompanying drawings, I haveshowntherein, plotted against time-asabscissae and kilowatt hours as ordilnates -iouriload lines 1, 2, Iii-and 4, respectively.

It will be seen that allzfour of these linesrepre- :sent a :rateaofenergy: consumption which is greater than an-ideal rate of energy-consumption, indicated-by a dot. and. dash line .5, which line just reaches F the maximum demand at the end oithe demand-period. This factis' brought out in another way by ithevdashed extension of the lines'.1,: 2,:3'T31nd 4,. all 'of'whi'ch intersects the uppermostlhorizontal' dashed line, or maximumwdemandt'linea before the end 1 of the demand periodmherebyindicating that the maximurrirdemand will be exceeded at the end of ithedemand' period ifmenergy continues to be used at :a'ny' oi'the-ratesindicated by these four lines. It will also be seen-that the load lines, 1, 2; Sand 4 are all modified at a particular inand 9 all finish at a value of kilowatt hours corresponding to the demand period.

Lines 1, 2, 3, 4, 6, 7, 8 and 9 illustrate graphically the essential principle of my invention, for it can be seen from these lines that, during the early part of the demand period, if the rate of energy increase is so high that if continued at that rate it will exceed the maximum demand, then at some intermediate value of demand the effective load value is reduced substantially in proportion to the rate of increase of energy use, so that for the remaining portion of the demand period the integrated energy will increase at a rate which will not cause an exceeding of the maximum demand at the. end of the demand period. The particular intermediate value of kilowatt hours or energy at which load v reduction takes place, may be set arbitrarily'and may be determined from studies of the loadcharacteristicsof the power circuit. One way of initiat ing my load limiting action at this particular value of energy is by actuating a circuit controller when this particular value of energy is attained. For example, a contact making power demand meter may have its contacts set so that when the kilowatt hours used by the circuit reaches this particular intermediate value, the contacts will be closed.

As previously stated, one way of obtaining the operation which is charted in Fig. 1 is by the use of time controlled circuit controllers operating in conjunction with an energy actuated circuit controller. Thus, for example, if the energy actuated circuit controller is actuated any time between the beginningof the demand periodland 'ated circuitcont'roller is actuated between times T1 and T2 not as much load is removed and the resultant load curve is shown by line '7, whereas if the energy actuated circuit controller requires still longer for its actuation and it is actuated any time between times T2 and T3 then the load which is removed is still less and the resultant load curve is that shown in line 8.

The difference inslope between lines 4 and'9 may be represented by the'removal of a load increment'which is not under time control, so that whenever the energy actuated circuit controller is actuated upon the occurrence of a predetermined fraction of the maximum demand, this load increment is removed. This feature is optional andmay ormay not be used in connection with the time controlled load increments.

It should, of course, be understood that Fig. 1 is merely for the purpose of illustrating the principles of operation of my invention and it represents ideal operation of the system in which the maximum demand is exactly attained at exactly the end of each demand period. .In actual practice, the load curves are never straight lines such as are indicated in Fig. 1, and the load value is usually fluctuating in character. Consequently, the amount of load which is removed between times T1, T2, T3, etc., must be determined from a study of the load curves of the system and judgment must be used in selecting the load increments torbe removed sothat in no case, or possibly only in very extreme and exceptional -cases, will the maximum demand be exceeded.

Fig. 2 illustrates graphically how-the principle of Fig. 1 may be extended SOflS'tO secure control and load reduction at more than one intermediate valueof energy consumption during the demand period. Thus, in this figure, the two intermediate horizontal dotted lines represent a low setting and a high setting of a contact making energy responsive controller, such as a contact making maximum demand meter. The arrangement is such that up to time T3 progressively less load is removed, provided the load,

curves have slopes of the order of curves 10, 11 and 12, whereas at later times T4, T and Te, respectively, progressively less load is removed provided the energy curves are of the order of curves 13, 14 and 15, respectively, and the arrangement is such that load is not removed in this latter case untila higher value of energy use has been obtained, which value corresponds to the high setting of the contact making device. In this manner, a double check is provided, for

if the energy consumption which has been reduced at the low setting is still too high when the high setting is reached, further reduction of load is made. At the same time, the arrangement of Fig. 2 has the advantage of being able to reduce load earlier in the demand period and this is desirable in cases where the energy consumption starts out at a high rate. In Fig. 2 only three load increments are controlled at times T1, T2 and T3, respectively, and only three load increments are controlled at times T4, T5 and To, respectively, and these latter increments may be the same as the increments controlled at times T1, T2 and T3, if desired. Furthermore, in Fig. 2 the additional, or fourth, load increment present in Fig. 1 has been dispensed with and only time controlled load increments are provided. However, additional load increments which operate whenever the high setting or the low setting is attained, may be added if desired in the same manner as is indicated in Fig. 1.

Fig. 3, which is a simplified, diagrammatic showing of an embodiment of my invention which operates in accordance with Fig. 1, consists of an electric power circuit 16 to which are connected a plurality of load increments 17, 18, 19 and 20, which are shown, by way of example, as electric motors. These load increments are provided with control switches, or contactors 21,

22, 23 and 24, respectively, for controlling theconnection and disconnection of their respective increments to and from the power circuit 16. These contactors are energized through a time controlled circuit controller 25 and through the contacts 26'of an auxiliary relay 27, which is controlled by an energy responsive circuit controller, such for example, as a contact making demand meter 28 connected to circuit 16 in the conventional manner. Meter 28 is provided with contacts 29 which are set so as to close when a predetermined fraction of the maximum demand allowable on circuit 16, as expressed in'kilowatt hours, has been reached, and these contacts are periodically reset to their initial position, in a well known manner, at the end of each successive demand period. Contacts 29 of meter 28 are connected in circuit with the operating winding of relay 27 across any suitable source of current supply, such for example as the circuit 16, so that when contacts 29 close relay 2'7 picks up thereby closing its contacts 26.

The time controlled circuit controller 25 may ,be of any well known type and as illustrated it atewith a vertically movable member 34 carry-- .rpaaavs :ings. arscdntact arm: :35. i Cooperafingxwith :arm $35.:are azseriesixof stationary contacts 36, 37,238 and 39.1 Contact 36 'is connected:to a-conductor 34m whichiiis icormected acrossithe. circuit 16 and :whicln'includes the ;contacts':"26. and the .oper- .atingcwinding of the :contactor 24. Contact 37, :bvhichzis: substantially 501 the; same length. as .con- ;tact 36;.is connected: to contactor12l', whilecontacts 38;,zand 39, "which; are 1 successively :shorter, are cmmectedirespectively .to .contactors :22. and 23. The operation of -the'.:circuit;controller -isisuchzthat=as thev motor .30 operates, .the memrlaer' 31wrotates in. a counter-clockwise. direction, as viewed in the-drawing; whereby the pin 33 .moves ithe member 34.11pwardly so that contact arm 35 successively-.disengages' contacts .39, .38, sand 37. :sUpon [slightly more: than a hali revolution of. member '31 the pin33 wilL'move-outfrom .wundernthexmem-ber 34 and this member willbe restored to the position shown: in the drawing :byxmeanssof a spring '41wwhereupon itz'will -engage ipin 32xand the above cycle: will be repeated.

The restoring mechanism 01. meter: 28 and'the motor=ofthe timing means 25, aresynchro- -nizedasorthatzthe contacts. 29 and thecontact .armw35'arer'in the position shown in the drawing at the-beginning of each successive. demand period.

iAlthough. Ivhaveshown-'power supply circuit 16 as energizing four load increments 1'7, :18, 19 ands-20, respectively; it-should beunderstood :that ass'many load increments: -as-desired may -be .supplied-from'thiscircuit and also additional uncontrolled rloads 149 may be supplied from. this circuit if desired.

The operation of: Fig. 3 is asfollows: Assuming-that circuitalfi is energized by. any suitable .sourcep-.of=..al-ternating current (not shown) the r-meter 28 willstart --registering the amount of energytakenibycthe load increments. and the motor.-30'of the timer '25 WillyODGl'fltG, thereby raising the contact arm 35. I If the total con- ..nected load to circuit 16-is so high-that the contacts '29 :close'within time T1 (see Fig. 1) contact arm 35* will nothave left contact 39-'and-consequently when thezcontacts'29 of meter 28 close "relay 27 is-energized: thereby causing the contacts 26 of-this'relayto complete the circuits for all -.four of :the contactors 21; 22,- 23 and 24, through contacts 37,.-38,- 39, and conductorw40 directly, "-respectively. As a result; all fourload increments 17,. -.18,- 19- and-.20 will be disconnected xirom the power circuitthereby reducing the load thereon. .At time T1 -(Fig. 1). contact 35 .leavescontact39aso thatii' the contacts 129 of relay281closebetween times T1 and Tz:only load -.increments =17, 18-and 20 'will be removed and increments 17 and-20 can be removed fromthe ncircuit. At time Ta-contact 35leavescontact 3'7 sothat thereafter the closure vof contacts 29 of the meter cause the disconnection of load increment-20 only, and load: increments 1'7, 18 and .19 remain connected to the circuit. It will thus be-seen that-the number of load'increments, or ...the amount of load, removedirom the circuit .varies substantially in proportion-to the rate at "which the integrated. energy demand on circuit 16' is-buildingup. Stated difierently, the amount -.of. load removed rvaries inversely with the time .requiredior contactss'29 of demandrmeter 28 to .close.

At the I end of thedema-nd period the contacts -of..the; time controlledfirelay .251 .and 'of': meter 28 are reset to the positions shown :in :the. drawings and the systemiiof Fig. 3 isrea'dy'to go through *anothericycleof .operatiomrexcept: that the relays 21,522,.231and24 havezto iberesetito their closed :zpositionsl For'providing thisuoperation each of :..the relays '21',;22,.'23and 24iis provided with latch :mechanisms 41, 1:42, z.43.a and 44, V respectively, which are operated by :electrosmagnets: 45, i .46,

4'7 and 48, respectively." These :electro-magnets are connectedrin: parallel with each. other in a control circuit which istconnected across the Lelectricepower circuit :16 through a set of back contacts 51 onimeteri 28. These back contacts 51 are! arrangedatoclose when the meter. is re- .set at thei'end'of each demand period. Consequently; -whenthistakes :place all'the electromagnets 45, 46;-i'47 and 48. are energized simul- =taneously thereby .releasingithe latches 41, 42, I43 and '44 andallowing the contactors 21, 22, 23 and 242to1 be'iresetsto their closed position as shown: in the drawing.

Fig. 4 differs IroniFig; B in that the load inicrement 20,-Wh1ChiSIl0ti under time control, has been omitted-and*auxiliarycontrol means have been added for'the three load: increments 17, 18

"and :19. This auxiliaryco'ntr'ol means comprises anLextra contact'52 on the meter 28 which contact. is adapted tocooperate-with'the movable one .ofcontacts 29 and which is adapted to be engaged thereby at a higher value ofenergy con- ;sumptionfthan isreq'uired for theclosing of the original :contacts' 29. Consequently, the meter is provided with two sets 'of' contacts which close respectively,=-at-relativelylow and relatively high values of energy consumption. The circuit controlled by contact 52 and the movable one of contacts 29- has='in it -the operating winding of a relay 53 having a set of contacts 54 "which'are in a circuit 55' which connects to the :contact 56 on-time controlled circuit controller 25. Cooperating withcontact 56 is a movable :arm 57 (corresponding to arm- 35) on the time delay circuit controller and-this arm 57 coop- -erates:not:o'nly with contact 56 but with progressively shorter#contacts-58,' "59' and 60 con- L'nected respectively in parallel-with contacts 3'7, 138 andt39.

".Theoperation"of'Fig. 4 -is such that if conif contactsL'291do. not close until after contact "arm 35 has left 'contact'37 none of the load inload increment 19 will remain connected tothe circuitsnt time Tz contact 35 leaves contact 38 -so thatbetweentime T2 andtime Ta only-loadcrements' will: be removed at this time; but if .themovzible 'one' of .contacts'29 engages contact 52- before contact57' has left-contact 60 all three ,of'theload. rements 17,18 and 19 will be re- 'moved by 'the energizationof' relays 21, 22 and 23-through-thecontacts--58, 59, 60, respectively. Sir'nilarly, if contact 52 is not engaged until'after contact 57 has left contact 60 but before it has "left contacts 58 and 59-then only load increments 18 and19'will beiremoved, whereasif contact 52 is engaged after contact 57-leaves contact 59 but before it leaves contact 58, only load increment 19 will be .removed.

..At. the .end .of. the. demandperiodthe meter 28 .is reset thereby closing contact '51 and causing .the electro-magnetic tripping means to -restore ..the:relays 21,.22 and23-to their closed position,

as has been described morei'ndetail in connection with Fig. 3. Y Referring to 'Figs.'4 and .2 together, the time from the beginningof the'demand period that isrequired for contact-35-to leave contact 37 corresponds to time-T1, thetime for 35 to leave 38 corresponds to time T2 and the time for 35 to leave 39 corresponds to time T3, whereas the time'requiredfor 57 to leave 60 is T4, for 57 to leave 59 is T5 and for 57tov leave 58.is Ts.

Fig. 5 shows a polyp-hase system comprising a generator 61 for energizing an electric power circuit 62 to which is connected a. variable load including load increments in the form of motors 63, 64 and 65. Forlimiting the maximum. demand on circuit 62 in the waylillustrated in Fig. 1, there is provided an automatic. system comprising a contact making demand meter 66 which, through a master'two-position relay .67

and an auxiliary relay 68, controls, three time delay relays 69, ,70 and 71, which in turn control respectively, the actuation of three twoposition relays-72, 73tand ,74 to positions whereby they cause individual contactors 75, 76 :and 77 to disconnect respectively the load increments 63, 64 and 65 from the main circuit 62. In addition, the contact making meter 66 operates through the master two-position relay 67 to con-.

trol two additional timedelay relays 78 and 79' which, in turn, actto restore the two-position relays 72, 73 and 74 to their original positions, thereby causing the contactors 75,, 76 and 77 to reconnect the load increments63, 64, 65, respectively, to the power circuit 62.

,This completes, ina general way, the description of the main elements of the system of Fig. 5 and its operation. The following is a more .detailed description of the various elements of the system and its operation.

The contact making demand meter 66 comprises essentially a pivotallymounted arm, or pointer, 78, which is driven through suitable driving mechanism, .such asa gear train 79, by

means of an electro-magnetically operated ratchet drive 80 from a watthour meter 81 connected to respond tothe energy-fiowin circuit 62 in the conventional manner. .Meter 81 is provided with a commutator arrangement 82 for producing intermittent,impulses whereby the ratchet drive 80 is actuated periodically at a rate of speed proportional to the speed of the meter and consequently proportional to the power flow, or rate of ;energy consumption in circuit 62 The arrangement issuch that. arm 78 is viewed in. the drawing, andits angular displace- .ment is proportional to the integrated energy flow in circuit .62. A spring 83 serves to bias the arm 78 in a clockwise direction and this arm is periodically-reset to a starting position by. any suitable means, suohas by a clutfilhing arrangement consisting of. a pivoted armiirs lawhich engages one of the gears of the gear train 79 which is slidably mounted so as to be capable of unmeshing with its cooperating gear. I The arm 84 is in turn actuated periodically by a cam 85 which" is driven by any suitabletiming means, such as by a timing motor 86, which may, for example, be a' small synchronous motorjof the electric clock variety. With'the above described arrangement, the arm'78 starts from a predetermined starting position and moves counter-clockwise for a predetermined time,

whereupon the cam 85 actuates the arm 84, thereby declutching the drive of the arm 78 and system.

allowing-the spring 83 to restore it to itsoriginal starting position. Arm 78 carries a contact "member 87 which is adapted to engage a fixed contact 88, which is resiliently mounted and which in turn is adapted .to engage another fixed contact 89 when contact 88 is flexed enough.

Contact making meter 66 is also provided with a' set of backcontacts 90 which are closed preferably simple standard relays of conventional design and in order to. avoid V needless repetition the identification of their various contacts and operating windings'is deferred until a detailed description of the operation and circuits is made. Similarly, auxiliary relay 68 and contactors 75,.76 and 77 are'simple conventional elements so'thatin order-to avoid unnecessary repetition only the details-of these devices which enter into the operation of the system will be described and this description will be deferred until the description of "the operation o'f the The time delay relays 69, 70,71,78 and 79' are also conventional elements of well known construction and as these relays are all similar in construction, only .relay 69 91111136 described in detail and the corresponding "elements of the remaining relays will begiven' corresponding reference characters- Relay -69 comprises essentially a small motor 91 whose rotatableelement carries a worm gear 92 which is adapted to be put'into engagement with'a gear wheel 99' for cooperation with the latch "member 98 whereby when gear 93 is turned clockwise through a given angle the pin 99 willengage the pivoted latch 98 thereby" releasing the arm 97. Cooperating with pivoted arm 97 is a fixed contactlOO which is connected to motor 91and thence to oneside of a suitable source o'f co ntrol current which-is marked with a negativepolarity rotated in. a counter-clockwise direction, as

symbol, for convenience. Magnet'94' is connected directly to'the pivoted arm 97 and thence to the negative side of the supply source as shown.

Relay 69 operates as followsf-If'the pivoted arm 97 is connected to the-other side of the source of current supply, motor 91 will be energized through contacts 100 and magnet 94 will be energized directly by the connection mentioned. Consequently, motor 91 fwill start to op- 98. After a predetermined time-pin 99 will engage the latch member, thereby causing it to release" member 97which in the meantime is being biased to a position away from contact 100 by means of the flexing of springmember 96 caused by the attraction of armature to .tuation of. these .two. relays.

the. magnet 94.=. As soon as arm 97 is released thecircuit'of the motor 91 is broken and consequently themotor comes to rest. arm. 97 is disconnected from the source of sup: ply current;the magnet 94 will be deenergized and armature will return to the position shown in :the. drawing either through gravity or by means of,a.suitable. biasing spring. This causes gear 92 .to. disengagegear 93 and gear.,. 93 will be restored to its initial position, byga small coil spring (notshown).

The main control contacts of. relay ,69 comprise .a movable contact 101, mounted on the spring member 96, and a cooperatingflxed contact 102.. In accordance with the above described operationof relay 69, thecontacts 101' and.102 will separate a predetermined timeafter the: energizationof the relay v69.

Relays. 70 and 71 differ from relay v69 only in thatitheupins :99, are set progressively farther.

andfarther back .so. thatzwhen relays 69, 70 and. .71 .are. .simultaneous1y .energized relay. 69

operatesnfirst, then relay. 70. operates and then.

relay. 71 operates. Similarly, relays 78' and 79' have .their;.pins.99. adjusted so that. these relays .operatezin a relatively much shorter time than eitheryofxtherelays .69, 70 and 71, but the pinscof' relays 78! and. 79 'are'alsoso set. that relay 78'Loperates slightly before. relay 79. The

time;settings.of relays '69, 70 and 71 correspond to .thetimes T1, Trand T3 of; Fig. 1. The purposeof relays .78 and .79'ris-to. provide .automaticsequential: restoration of the .load increments 63,64 and 65.to thepower circuit. This sequentiahrestoration isfor. the purpose of preventing. momentary overloads. on the circuit. whichmight .occur...if. all theload increments were simultaneously)reconnected.to. the .circuit. One otherdiiference betwen relays .78; and 79" andthe. relays 69, 70 and 71 is that: the two firstumentioned .rela'ys have a direct connection 1 between the-:arm...97. and the resilient arm 96. This is inorderto insure that arms 96 of relays. 78. and...79" will be energized upon the ac-.

this:.will beexplained more. in detail in connection with the operation of the systemq The .operation'of. the entire system asa whole,

together; with .a detailed tracing of theessential-n circuits; of the. system; is..as follows: Assume that generatorfil isbeing driven by; any suitable prime mover (not shown) and that a suitable":

source of control current isapplied between the points in the control circuit.whichare marked with'a plus and minuspolarity symbol. These symbols are provided merely for-convenience in..

tracingthe circuits and inactual practice itis preferable to use an alternating current source of control current .so as. to provide better synchronization of the various motors of the relays and de-.

mand meter. Under the above described condi-' tions, contactors75, 76 and 77 will be energized from the positive side of the source of control ratcheting mechanism 80, whereby the demand. meter pointer 78 is driven in a-counter-cloclb.

If now they The. purpose for wise direc.tion.,.At thewsamevtime, a circuit is. completed" frompthe .positive side of the control source through-a conductor 103, .to motor 86, wherebythis'motor is energized and cam. 85 is driven in the proper direction so that at .the end .of.wthe.,:demand.interyaLit willengage arm 84 and cause. resetting ofthe arm-.-78,:as previouslyv described. ',.Also-.atf the same time, there is a circuit completed- ,from conductor 103- througha .set' of; contacts=:108. on master two position relay.;.67, thencethrough conductors 109- and 110 to the-arms .97 of time delay. relays 69, 70 1 Consequentlmythese three time-delay and .71. relays willpbe, simultantously energized and will start their1.-timingoperations-. in the manner which has. already been described in detail above;

Assume now: that. the total. load on circuit; '62" is high .enough so thatthe arm 78of contact 1 makingdemand meter 66 moves counter-clockwise; far enough so. thatcontact a 87 engages contact 88. No circuit is completed/when this vban-- penseand contact '87 'continuesnmovlng in: a counter-clockwise direction :thereby flexing contact. 88; until itengages contact 89.- Thereupon a .circuit.is completed from the. positive side of the control. source: through conductor 103, -contacts:108,:condu0ton109; contacts 8'2, 88 and 89;;

a .conductor'lll', through the operating winding. of relay 68 to the negative side of thercontrol This causes -actuation-of relay 68 source;

wherebya set-:of-holding contacts 112 thereonare closed. These. contactsare connected across contacts 88 and 890i the meter so thatshouldv contacts 88 and {89 become disengaged the.

energizing circuit of relay: 68 is :completed through :the engagement of:contacts;87v and 88;

and thence through the contactsv112'. The-pure.

pose of this arrangement-.yisto preventa chattering operation of relay 68 which could otherwise-take place if :it-were. energized directly by the engagement ofconta'cts 87 and 88 due. either to vibration of the contactsof-meter 66v onto. the

fact that contact 87 has. an-intermittent motion:

dueto. thewratchet and pawl type. of drive employed for-moving :it. However, with the arrangement; shown,--. as soon as. :.contact, 88 en- I gages contact. 89. the relay68 is energizedand it williremain'energized ieven though,.contacts- 88 and. 89 are-thereafter intermittently engaged.

and forms-no part1 of;the present inventionrexsystem as a whole due to its presence.

The actuationof relay 68 also closes another set of-contacts 113 thereonand the closure of these contacts serves to connect'the positive side of the directcurrent controlsource, the;.connec-.

tion of which .to conductor. 110 has alreadybeen traced,:to a conductor 114 to which isconnected the. contact. 102 of" relay 69',- a contact 115 of relay 701 and.;a contact 116 of relay. 71.

Assume now [that relay. 68 has. been actuated before any ofzthe time delay relays-69, 70. and. 71 1 complete their time 'cycle.

The result is '50 'I'hisfeature; is, in and. .of itself,-:old' in theart:

-cept.insofar. as itimproves the: operation of the thaticontrol. currentflowsqfrom the positive side of- .the control. source throughconductor 114v in a manner which has already been traced, thence first through contacts 102, 101, throughqmember 96 to :a conductor 117, a plug. and socket quick-detachable connection. 118, a conductor 119, aset of contacts 120 on relay 72, and an operating winding 121 on this relay. Energize tion. of operating winding .121 causes relay 72 to assumetheopposite, position, tothat shown in the drawing; whereby contacts 105are opened, thereby deenergizing contactor and disconnecting motor-63 from power circuit62. At the same time current flows from conductor 114, through contact 11 5on're1ay 70, and movable contact 122 thereon, through the arm 96, thence a contact 116 on relay 71, a movable contact 128 thereon, thence through the arm 96, a conductor 129, a plug and socket connection 130, a conductor l3lycontacts 132 of relay 74, and an operating-winding133 thereon. This causes relay 74' tobreak its contacts 107 thereby deenergizing relay 77 whereby motor 65 is disconnected from the main power circuit 62.

It will, of course, be obvious from the above description that if contacts 88 and 89 of the contact making demand meter are not closed untilafterrelay 69 has gone through its cycle, that is to say after time T1 but before relays 70 and 71 have been actuated, only motors 64 and 65 will be removed, whereas if both relays 69 and 70' have gonethrough their cycle of operation before contacts 88 and 89 are engaged but before time delay relay 71 has completed its cycle, only motor 65 will be removed from the power circuit. After all three relays have gone through their time cycle the engagement of contacts 88 and 89 merely causes the operation of relay 68 but as'the main contacts of the time delay relays 69, 70 and 71 are open no load control or removal takes place.

At the end of the demand period cam engages the arm 84 thereby causing disengagement of the gears 79 of the driving train for the arm 78 and allowing spring 83 to restore arm 78 to its starting position: This causes thearm 78 to bridge the back contacts and of course also causes disengagement between the three contacts 87, 88 and 89; This disengagement causes a deenergization of the relay 68. The bridging of the back contacts 90 completes the circuit fromithe positive side of the control source through conductor 103, contacts'90, a conductor 134, a set of contacts on master two position relay 67 and an operating winding 136 thereon. Energization of this winding causes this relay to snap over to its other position thereby breaking the connection between contacts 108 and completing the connection between a set of contacts 137. The breaking of the connection between contacts 108 deenergizes the magnets 94 of the relays 69, 70 and 71, thereby causing these relays to be restored to the positions shown in the drawing. The closing of the contacts 137 on relay. 67 completes a circuit from the positive side of the control source through conductor 103,

the contacts 137 and aconductor 138 to the time delay relays 78' and'79. Consequently these relays start their timing cycle immediately. At the same time, a parallel circuit is completed from a contact 139m relay 78', to a contact 140 thereon which is in engagement with contact 139, thence through a conductor 141, through the plug and socket connection 130, a conductor.

142 and through a set of contacts 143 on relay 74 to an operating winding 144 on this relay, it being remembered that this relay is now in. the

opposite-position from that shown in the draw ing, so that the contacts 143 are closed. Consequently, relay 74 is immediately snapped back to the position shown in the drawing thereby bridging contacts 107 thereon, whereby the energizing circuit for relay 77 is completed, thereby reconnecting motor 65 to the power circuit. T Inla relatively short time relay 78 goes through its cycle and contact 139 leaves the contact 140 and engages a stationary contact 145 on this relay. This completes a circuit from contact 145 through a conductor 150, plug and socket connection 124, a conductor 151, contacts 152 on relay 73 and an operating winding 153 thereon. Energization of coil 153 snaps the relay 73 back to the position shown in the drawing thereby bridging contact 106 thereon and causing reenergization of contactor 76 and. consequent reconnection of motor 64 to the power circuitJIn a short time after the operation of relay 78', relay 79 completes its cycle, whereby a set of contacts 154 thereon are closed. This completes two parallel circuits. One circuit is through a conductor 155, plug and socket connection 118, a conductor 156, contacts 157 on relay 72 and-an operating winding 158 thereon.

The energization of winding 158 causes the two.

position relay 72 to snap to the position shown in the drawing, thereby bridging its contacts 105 and causing thereenergization of the contactor 75 and a consequent reconnection of the motor 63 to the main power circuit 62. parallel circuit controlled by contacts 154 is through a conductor 159, a set of contacts 160 on master two position relay 67 and an operating winding 161 thereon. Energization of Winding 161 causes the relay 67 to be snapped back to the position shown in the drawings; in which position it will remain for the rest of the demand period due to the fact that during the operation of the relays 78 and 79 the contact arm 78 of the contact making demand meter 66has left the contacts 90 so that these contacts are no longer bridged and a circuit will not be completed through the contact 135 and the winding The other 1360f relay 67 when it snaps back to the position shown in the drawings.

From the above description it will be seen that when all three motors 63, 64 and 65 are disconnected from the circuit they are disconnected in that order, but that they are restored in the order 65, 64 and 63. That is to say, they are restored in reverse order from the order in which they are disconnected. However, they may either be made to be restored in the same order in which they are disconnected by simply reversing the connections of the conductors 141 and to the plug and socket connections 130 and 118, respectively. Furthermore, by interchanging the plug and socket connections, which connections are purposely made interchangeable, italS possible to make any one of the three motors the first one to be removed and the last one to be restored, or vice versa. Similarly, any one of the motors may be made the second one to be removed and the second one to be restored.

While I'have shown and described particular embodiments of my invention, it will be obvious to those skilled in the art that changes and modifications may be made without departing frommy invention, and I, therefore, aim to cover in the appended claims all such changes and modifications as fall within thetrue spirit and scope of myrinvention.

tion to the magnitude of the average rate of in-,

crease of the integrated ,energy. ,consumptionof. said load, said. meansincluding a time controlled element. g

2. In combination, an electric power circuit, a load connected thereto, and means responsive'to the load on said circuitfor reducing the magni tude of said load substantially in proportion-to the-magnitude of the average rate of increase of integrated energy consumption of said load during the first part only of the demand period for said power circuit, said means being jointly controlled by a time controlled circuit controller.

3. In combination, an electric power circuit, a load connected thereto, a circuit controller, means responsive to a predetermined integrated energy flow in said circuit for actuating said circuit controller, control means for reducing the efiective value of said load on said power circuit in response to actuation of said circuit controller, and time controlled means for varying the magnitude of the effective reduction of load substantially inversely with the time required for the actuation of said circuit controller.

4. In combination, an electric power circuit, a load connected thereto, a circuit controller, means responsive to the energy flow in said circuit for actuating said circuit controller when a predetermined integrated amount of energy has passed through said circuit, time controlled means for periodically resetting said circuit controller, control means for reducing the effective value of said load on said power circuit in response to actuation of said circuit controller, andtime controlled means for varying the magnitude of the effective reduction of load substantially inversely with the time required for the actuation of said circuit controller.

5. In combination, an electric power circuit, a load connected thereto, a power demand meter connected to said circuit and having a circuit controller which is set to be actuated upon the attainment of a predetermined fraction of the maximum demand of said circuit, and means responsive to the actuation of said circuit controller for removing a fraction of the load from said circuit which fraction varies inversely in magnitude with the fraction of the demand period required for the actuation of said circuit controller, said means including time controlled circuit controlling means.

6. In combination, an electric power circuit, a plurality of load increments connected to said circuit, a contact making demand meter connected to said circuit, and having its contacts set to close upon the attainment of a predetermined fraction of the maximum demand of said circuit, means responsive to the closing of said contacts for removing a plurality of said load increments from said circuit, and time actuated circuit controlling means for varying the number of load increments removed inversely with the fraction of the demand period required for the closure of said contacts.

7. In combination, an electric power circuit, a load connected thereto, a power demand meter connected to said circuit and having a circuit controller which is set to be actuated upon the attainment of a predetermined fraction of the allowable -maximumdemand -of "saidcircuit} means responsiveto the actuation'of said circuit L controller-forremovingpart of said load from said circuit; and means for progressively reducing-the amount of load so-removed in accordance with increase-in the time-requiredfortheactuationofsaid circuit controller:-

8. In-oombination, an electric power-circuit,'a plurality of load-increments connected thereto, a power-demand meter having a circuitcontrollerwhich 'is actuated upon the' attainment of a predetermined-fraction of the -maximumdemand of said-=circuit;-a plurality of: circuits under thecontrol" ofsaid circuit'controller for removing the respective loadincrements from said 1 power circuit, and time controlled circuit controllers in said circuits for successively and cyclically incapacitating their respective circuits for removing their respective load increments from said power circuit.

9. In combination, an electric power circuit, a load connected thereto, a power demand meter connected to said circuit and having a plurality of circuit controllers which are set respectively to be actuated upon the attainment of different predetermined fractions of the maximum demand of said circuit, means responsive to the actuation of one of said circuit controllers for removing a fraction of the load from said circuit which varies substantially inversely in magnitude with the fraction of the demand period required for the actuation of said circuit controller, and means responsive to the actuation of the other circuit controller for removing a fraction of the load from said circuit which varies substantially inversely in magnitude with the fraction of the demand period required for the actuation of said other circuit controller.

10. In combination, an electric power circuit, a load connected thereto, a power demand meter connected to said circuit and having a plurality of circuit controllers which are set respectively to be actuated upon the attainment of different predetermined fractions of the maximum demand of said circuit, means responsive to the actuation of one of said circuit controllers for removing a fraction of the load from said circuit which varies substantially inversely in magnitude with the fraction of the demand period required for the actuation of said circuit controller, and means responsive to the actuation of the other circuit controller for removing a fraction of the load from said circuit which varies substantially inversely in magnitude with the fraction of the demand period required for the actuation of said other circuit controller provided said fraction of said load has not been removed in response to the actuation of the first circuit controller.

11. In combination, an electric power circuit, a plurality of load devices, individual switches for connecting and disconnecting said load devices to and from said power circuit, individual two position relays for controlling said switches, a plurality of parallel circuits for controlling respectively the operation of said relays in a manner to cause said switches to disconnect said load devices from said power circuit, individual time delayed acting relays in said circuits, said relays having different time settings, an auxiliary relay, a master two position relay, a connection for energizing said time delayed acting relays through said master two position relay when said master relay is in a given position, a connection for energizing said parallel circuits through said auxiliary relay and saidmaster relay when the latter is in said given position, a power demand meter connected to respond to the power demand on said circuit, said meter having a pair of controlcontacts which are set to close when a predetermined fraction of the maximum demand of said circuit is attained, said meter also having a set of back contacts which are periodically and momentarily closed at the end of each successive demand period, a circuit completed of other time delayed acting relays with different time settings, circuits completed through said master relay when it is in said other position for energizing said other time delayed acting relays, circuits controlled by said other time delayed acting relays for causing said two position relays to assume positions for causing said switches successively to connect said load devices to said power circuit, and a circuit controlled by the last one of said other time delayed acting relays to be actuated for energizingsaid master relay in such amanner as to restore it to said given position RICHARD H. KAUFMANN. 

